Advanced heart failure represents a major unmet clinical need, arising from the loss of viable or fully functional cardiac muscle cells. Despite optimum drug therapy, heart failure is a leading cause of mortality in America. Generating functional myocardial tissue from a renewable patient-specific source would allow for the development of disease specific cellular models for pathway identification and drug development. It would also lay the foundation for therapeutic cardiac regenerative medicine. We propose to integrate the unique expertise, reagents, and protocols from four leading laboratories in cardiac stem cell biology and development (Chien/Wu), human ES and IPS technology (Melton), and cardiac tissue engineering (Parker), to generate patient-specific myocardial tissue as cellular models for human cardiovascular disease, and as a foundation for cell-based regenerative therapy. Accordingly, the specific aims of our proposed project are the following. AIM 1: Identify non-cell autonomous signaling pathways that control cardiovascular progenitor cell (CVP) expansion and differentiation. We hypothesize that specific non-cell autonomous signaling pathways control murine CVP expansion and differentiation. AIM 2: Determine if murine iPS-derived CVPs recapitulate normal cardiac development and can be used to generate functional myocardial tissue in vitro. We hypothesize that IPS derived cardiac progenitors are similar to ESC-derived cardiac progenitors in developmental potential and functional characteristics. AIM 3: Isolate and characterize CVPs from human ES and IPS cells. We hypothesize that during human ES and iPS cell differentiation, cardiac myocytes are generated by the commitment of cardiac progenitors into CVPs which then differentiate into fully mature ventricular myocytes. AIM 4: Generate cellular models for human cardiovascular disease such as X-linked cardiomyopathy (i.e. cardiomyopathies caused by dystrophin mutations such as those in Duchenne's and Becker's muscular dystrophy). We hypothesize that disease specific CVP will recapitulate diseased myocardial phenotype, as well as diseased myocardial phenotype. This will serve as a platform for genetic pathway discovery, drug design, and regenerative cardiovascular medicine.